1. Field of the Invention
This invention relates to a graphic data processing system and, particularly to a graphic data processing system for retrieving or displaying data concerning a graphical form which is entirely or partially contained in a designated three-dimensional space, at a high speed.
2. Description of the Related Art
In a CAD system, there is frequently executed a process in which only the data concerning a graphical form contained in a designated three-dimensional space is displayed or retrieved out of multiple graphical forms, each graphical form constituting a three-dimensional figure. For instance, a process is frequently executed in which a graphical form displayed on a screen is entirely or partially enlarged, rotated, or moved to other display sections on the screen. In this process, it is required to discriminate whether a graphic element of each individual graphical form constituting the three-dimensional figure is contained in a designated region. In an existing CAD system, it is discriminated whether the graphical form is entirely or partially contained in the designated region with respect to all the stored graphic data concerning the graphical forms. Based on the discrimination result, the graphical form which is not contained in the designated region is neither displayed nor retrieved, whereas the one contained therein is displayed or retrieved.
However, a large number of processing steps are required in the conventional system in which it is checked in detail whether the graphical form is contained in the designated region with respect to all the graphical forms. Accordingly, the conventional system requires substantial time to obtain a complete display or retrieval result, thereby presenting the problem of a reduced working efficiency.